Democratic Gov. Janet Mills on Friday signed into law a suite of gun safety legislation approved by lawmakers after the deadliest mass shooting in state history, expanding background checks for private sales of weapons, bolstering the state’s “yellow flag” law, criminalizing the transfer of guns to prohibited people and expanding mental health crisis care.

The governor told lawmakers during her State of the State address that doing nothing was not an option after an Army reservist with an assault rifle killed 18 people and injured 13 others in Lewiston on Oct. 25.

The bills drew opposition from Republicans who accused Democrats, who control both legislative chambers, of using the tragedy to advance proposals, some of which had been previously defeated. Mills said Friday the proposals would improve public safety while respecting the state’s long traditions of gun ownership and outdoor heritage.

“This law represents important, meaningful progress, without trampling on anybody’s rights, and it will better protect public safety by implementing reasonable reforms and by significantly expanding mental health resources,” Mills said.

The new law signed by the governor doesn’t require universal background checks but it does require background checks for people who advertise a gun for sale on Craigslist, Facebook Marketplace or elsewhere. Sales would be required to be checked against the National Instant Criminal Background Check System, as is required for commercial sales at federally licensed firearm dealers, the governor’s office said.